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Astronomers have spotted a giant blinking star, 100 times the size of the sun, lurking near the heart of the Milky Way.
Observations from the telescope revealed that within a few hundred days, the huge star, which is over 25,000 light years away, faded 97% and then slowly returned to its former brightness.
The unexpected and dramatic darkening was likely caused by an orbiting planet or a companion star surrounded by an opaque dust disk traversing past and blocking light that would otherwise have reached Earth.
“It seemed like it came out of nowhere,” Dr Leigh Smith of the University of Cambridge’s Institute of Astronomy said of the star’s sudden fading. It started to fade in early 2012 and was almost gone by April of that year before recovering over the next 100 days.
Astronomers have noticed the mysterious obscured star in data collected by the Vista Telescope, operated by the European Southern Observatory in Chile. The instrument has observed a billion stars for nearly a decade looking for examples of varying luminosity in the infrared region of the electromagnetic spectrum.
When scientists find variable stars that don’t fall into the established categories, they call them “what is this?” “Or” WIT “objects. Their latest discovery is called VVV-WIT-08.
Because the huge star was in such a dense region of the galaxy, researchers wondered if an unknown dark object could have strayed in front of it by chance. The simulations suggested that this was highly unlikely without an implausible number of dark objects floating around the Milky Way.
It is much more likely that the telescope view of VVV-WIT-08 was obscured when a dusty disc around an orbiting planet or a second star interfered. The calculations of astronomers, reported in the Monthly notices from the Royal Astronomical Society, suggested that the disc was tilted to resemble an ellipse of the Earth and must be gigantic, having a radius of at least a quarter of the distance from Earth to the sun.
This is not the first blinking star discovered by astronomers. A huge disk of dust causes the giant star Epsilon Aurigae to drop by about 50% every 27 years. Another star known as TYC 2505-672-1 is part of a binary system and is eclipsed by the disk around its companion star every 69 years. It is not known when VVV-WIT-08 will decline again, but astronomers believe it will happen in the next 20 to 200 years. Two more flashing stars were spotted alongside VVV-WIT-08, but researchers have fewer details on this.
The wave of discoveries will help astronomers understand what appears to be a new class of “flashing giant” stars. “Once you start to build collections of several of these items, you can examine their properties as a whole and unravel the mysteries of the origin of these records,†Smith said. “It allows us to learn how these systems evolve and what they do at the end of their life.”
